Dear MEEP users,
I'm trying to use meep to calculate dispersion of surface plasmon wave guided
by thin gold film surrounded by dielectrics. Usually there are four modes
suported by this kind of structure, ie. symmetric bound mode, the symmetric
leaky mode, the antisymmetric bound mode, and the antisymmetricleaky mode. I
want to calculate the dispersion curve of the two bounded mode, but with the
epsilons I have chosen for the surrounding dielectrics in the following ctl
file, I can only get antisymmetric bound mode for the first band, I guess the
second and third band corresponding to the symmetric leaky mode and the
symmetric bound mode respectively, but when I plot the field profile of the
third band of a given k point, it does not seem to be a symmetric bound mode,
furthermore if I increase the resulotion to 800 I cann't get the first band for
some k ponits. I have also simulate the same structure with different
surrounding dielectrics, some times I got symmetric bound mode easily and
hardly find antisymmetric bound mode. I have tried with different pml width,
resulotion, runtime, gold definition, Courant, source center and size. and
still couldn't solve this problem. Any help or idea is appreciated.
Sincerely!
huoliang
(define-param sx 5) ; size of cell in x direction
(define-param dpml 1) ; PML thickness
(set! geometry-lattice (make lattice (size sx no-size no-size)))
;(set! Courant 0.2)
(define substrate (make dielectric ( epsilon (* 1.42 1.42))))
(define analyte (make dielectric (epsilon (* 1.33 1.33))))
(set! eps-averaging? false)
(define omega_d (/ 1 0.138)) ; plasma frequency of Au in Drude model
(define Au ; definition of material dispersion
(make dielectric (epsilon 9.75)
(polarizations
(make polarizability
(omega 1e-20) (gamma (/ 1 13))
(delta-epsilon (* (* omega_d omega_d) 1e+40)))
)))
;(define omega_d 7.050) ; plasma frequency of Au in Drude-lorentz model
;(define Au ; definition of material dispersion
; (make dielectric (epsilon 5.967)
; (polarizations
; (make polarizability
; (omega 1e-20) (gamma 5.310E-02)
; (delta-epsilon (* (* omega_d omega_d) 1e+40)))
; (make polarizability
; (omega 2.168) (gamma 3.498E-01)
; (delta-epsilon 1.09)))))
(set! geometry
(list (make block (center (- (/ sx 4)) 0 0)
(size (/ sx 2) infinity infinity)
(material substrate))
(make block (center (/ sx 4) 0 0)
(size (/ sx 2) infinity infinity)
(material analyte))
(make block (center 0 0 0) (size 4e-2 infinity infinity)
(material Au))
))
(set! pml-layers (list (make pml (direction X) (thickness dpml))))
(set-param! resolution 200)
(define-param fcen (/ 1 0.63))
(define-param df 1.2)
(set! sources (list
(make source
(src (make gaussian-src (frequency fcen) (fwidth df)))
(component Hz) (center 0 0 0) (size 0.05 0 0) ) ))
(define-param k-interp 19)
(define-param k-points (list (vector3 0 2.15 0 )
(vector3 0 2.36 0)
))
(set! k-points (interpolate k-interp k-points))
(run-k-points 60 k-points)
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